<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body{
            height: 5000px;
        }
        .box1{
            width: 100px;
            height: 100px;
            background-color: red;
            position:fixed;
            right: 100px;
            top: 100px;
        }
    </style>
</head>
<body>
    <div class="box1"></div>
    <span>我是span标签</span>
</body>
</html>